Nocturne
by AllusionToAnIllusion
Summary: The wind howls outside as the sound of rain against glass envelopes them, none of the usual city lights casting their glow over the dark loft. Kate presses further into Castle, letting his warmth settle in her bones and leech into her soul.
1. Chapter 1

_For Pau,_

_even if it's not your birthday anymore I'm still gonna celebrate it_

* * *

Tapping a staccato rhythm on his leg with her socked feet, she tries to focus on the ink stained pages. Candlelight flickers across her vision, making the pages flash capriciously before retreating back to the shadows. She gives up on the tapping, starts kneading the balls of her feet into the muscle of his thigh. Rain pelts against the windows as the wind scrapes against the glass, making them rattle, and she hopes they hold. The hurricane's been howling outside all day, buildings groaning with the force of it.

They've been wrapped in blankets since the morning, locked inside his loft because it was going to be fun. It was supposed to be a sort of adventure, the hurricane trapping them inside his loft with no electricity and no heat. But they've been here all day and all he's wanted to do for the past two hours is work on his edits, pen and paper like the good old days, he says. At first she found it entirely too sexy, the swipe of his fountain pen over the wrinkled sheets, but it's been two hours and she's vibrating with pent up energy.

She flexes her ankles, points her feet like her ballet teacher taught her when she was seven, and her toes end up wedged between his jeans and the couch cushion. Wriggling them, she tries and inevitably fails to focus on the book, distracted by the heat of his leg and the flicker of light over the aged paper. She lifts her big toes, presses them further into his thigh and relishes in the tightening of the muscles there.

"Kate." His tone is meant to warn her but it only spurs her on, anticipation filling her chest at the fact that she's finally managed to distract him. She rolls her ankles, lets her feet drift further into the space between the couch and his leg. His fingers come to her ankle, curl there and stroke the sharp jut of her bone, tracing her fibula until it disappears into the muscle of her leg.

She looks up at him, sees what the candlelight does to him. He's all harsh cheekbones and warm eyes that slope into a sharp nose. He looks soft yet somehow sinister and it completely does it for her. She takes advantage of her feet under his thigh, rises up just as she reaches to put the book on the coffee table. Her lips come to his shoulder, as far as she can reach, and she darts her tongue out against the cotton of his t-shirt. She waits, leaves her open mouth there until he cants into her and suddenly she can reach the column of his throat.

Her lips trail up his neck, wet and teasing, and she nibbles his pulse point as it thumps steadily under her lips. She sees his hands clench, fingers tightening around his pen as he tries to continue editing. But then her teeth sink into the hollow of his collarbone and she all too clearly spots the trail of ink he didn't intend to mark his page with.

She feels him swallow, his throat working and Adam's apple bobbing under her tongue as she sweeps her mouth across his skin and brings her hands to his chest. She lets her fingertips ghost over his chest, revels in the warmth he provides as her nails, pale paint cracking like an old sidewalk overtaken by roots, scratch their way over his abdominal muscles.

They contract under her touch and she hears a sharp exhale somewhere above her, feels warm breath rustle her hair and coil around the shell of her ear. She smiles into his collarbone, lips pressed tightly to his skin and she tastes that particular swirl of salt and musk she's come to know him by. Nuzzling her nose further into his warm skin, she darts her tongue out to taste more of it, entirely addicted in too little time.

She's about to dip her hand lower, _really_ get him to pay attention to her, but then his head is turning and his lips are coming closer until they're roughly pressed against hers and _mmm yeah there we go_. She sucks his tongue into her mouth because she's been waiting for this for _two hours_ now and that is entirely too long a time to be staring at his dexterous fingers with her imagination as the only option. When he pulls away, making sure he's out of range so she can't follow, he smirks at her and trails his fingers over her calf.

"Waiting to do that for a while, huh?" She huffs at him, doesn't deny it because she knows it's pointless. She just showed him exactly how long she'd been waiting. "You know I love it when you get impatient."

"Yeah, well, it was only fair." There's laughter in his eyes, a mirth she loves seeing there. Especially when she puts it there.

"Only fair that you seduce me when I'm trying to get work done?" He raises and eyebrow at her but she knows better.

"What do you call the five years you've been following me around?" He scoffs at that as if he's truly offended by her accusation, as if this beautiful thing between them didn't start out as a way to get into her pants.

"Work."

"Yeah, sure, Castle." She shakes her head at him, pulls her feet out from beneath his legs and curls them under her own.

"Siren."

"Philanderer."

"Temptress."

"Gigolo."

"Heathen."

"Not related. I win." She grins at him, wiggles in her seat as she preens. Pouting, lower lip protruding like a little boy, Castle sulks back in his seat, an author defeated by his girlfriend at a game of words.

"I still win when we play Scrabble." She leans into him, sets her chin on his shoulder and casts teasing eyes up at him.

"We've played Scrabble once." His eyes are crinkled at the edges, laugh lines radiating from the corners, reminding her of tracking birds in the winter when she was little, following the tiny footprints they left in the snow only to come to the end and see that they'd simply taken flight.

"Yeah, and I won." She laughs at him, truly delighted with his childishness even after being cooped up with him all day. Gusts of wind press up against the glass of the windows, howling to be let in but she just curls into him. He picks up his pen again, probably to resume editing, and she can't hold in the groan because she's not good at being this still. He chuckles, crosses something out before looking down at her.

"How bored are you right now?" She opens her mouth to say she's not, that she's perfectly content to sit here for another two hours and watch him trail ink across wrinkled paper, but she knows he can feel it in the way her body hums with energy.

"Extremely." She sighs, sits up straighter and fiddles with the hem of her shirt because at least then she'll be doing _something_. He cocks his head to the side, studies her for a moment before hopping off the couch. Cold rushes into the suddenly unoccupied space by her side and she pulls the blanket tighter, wraps it around her to trap the heat.

She sees the dark form of him where the candlelight doesn't reach, a grey shadow against the black of his kitchen. It's haunting, how dark it is in the spaces with no candles, the city's flashing neon signs and lighted windows temporarily out of commission. She hears him rummaging around for something in the cabinets, the slide of drawers and sounds of him closing his fingers in one of the doors. Then a light clicks on and his face lights up, dark shadows under his eyes and nose as he brings the lantern he must have collected over years of indoor camping trips with Alexis under his chin.

"Come on, Beckett." He makes his way to the front door, beam of light guiding the way as she unwraps herself and hesitantly follows him.

"Castle, where are you going? You can't leave the building," she catches his arm, pulls him back so he'll look at her even in the inky black, "it's horrible out there." He twists his arm out of her grasp, empty hand falling to his side, continues on until he's passing through his front door and the light shines out ahead of him into the black.

"Who said anything about leaving the building?"


	2. Chapter 2

_Thanks to Elle for making me fix my own problems and Bee for encouraging me to review her instead of writing this. You guys are true friends. _

_And to Pau, happy (seriously, horribly, absolutely terribly) belated birthday, my dear!_

* * *

She's never been in this part of his building, only the route from the lobby to his door familiar to her even after all these years. Holding the lantern like a famous explorer, expression too serious for the childish mirth in his eyes, he leads her through hallways and stairwells. It's strange, following him through the unfamiliar darkness when it's usually the other way around. She follows the strong lines of his body, traces the dark outline with appreciative eyes.

"You checking me out?" He breaks the silence, looks back with a grin in his eyes as she smirks.

"Just your ass." He chuckles, his shoulders and the lantern dangling from his hand shaking with his happiness. Because it's raining and windy and absolutely horrible but he's taking her on an adventure through his apartment building. It bubbles up inside of her, how much she needs this, the joy he brings. She cocks her head to the side, smile brimming with light as she takes a swing at his ass. Her hand connects with a crack, a hard slap resonating from his jeans.

He jumps, a surprised little hop, and brings his free hand to cover his butt as he turns to her. Eyes wide, overflowing with a new sort of surprise and absolute joy, he smiles at her. The lines of his happiness crisscross over his face, straining to hold all of it as it fills every crevice. She feels her own joy spreading, leaking out in sharp barks of laughter as he comes to her, drawn by the call of her mirth.

He kisses her then, his smile pressed to hers and she can't help but laugh into his mouth. She darts her tongue out, feels the pull of his teeth on her lower lip, but there's just so much joy inside of her that wants out and she can't hold it all. The bursts of laughter grow stronger, pushing her back against the wall as he follows, his own laughter loud and right against her pulse. They're both shaking with it, with their shared laughs that burn bright on her skin.

Her hands find purchase on his shoulders, steadying them both as the shaking subsides. He ventures out from the cave of her neck, eyes finding hers in the darkness as the lantern glows somewhere under them. His eyes are still dancing with it, but his face is no longer overflowing.

"C'mon, Kate," he takes her hand and pulls her away from the wall, "we're almost there."

"Where, exactly, is _there_?" She squeezes his hand, rubs small circles in that space between his index finger and thumb with her own. It's a rough patch, which she always found surprising for a man who types for a living, but there's a part of her that jumps at the coarse feel of the skin. The feel of it pressed to her lips, under her fingertips when they watch TV, against her roaming tongue because he absolutely can't pay attention to anything else when she does that – it's one thing she didn't dream about for all those years, something she didn't expect, and that makes it beautiful.

"Nuh-uh, no spoilers." The tease in his voice is impossible to miss, the childish whine of _I know something you don't_, but she also hears his excitement to show her, to share with her.

"Yeah, like when you said no spoilers for your book?" His head swivels to her, shock in his eyes as his expression turns affronted.

"It's not my fault that I got stuck and you were the closest sounding board. You know that I can't be expected to adhere to rules when I have an idea." She smirks because _yeah, she does_ but he can pout for a little while.

He turns a corner and she notices that there aren't any apartments in this part of the building, only the occasional door or big glass window looking into some sort of amenity that her building definitely doesn't have. He stops at one of the doors and she almost walks right into him in the darkness, the lack of movement of his hand her only signal to stop walking. He reaches out, places his hand on the doorknob and she wrinkles her nose in confusion.

"Castle, you need a keycar–"

"Trust me." He turns the doorknob and suddenly the door is cracked open, his almost imperceptible hiss of victory filling the silence. "See. Power's out and these aren't battery operated so they're down for the count." She almost laughs at the relief coloring his voice, can imagine him trying to open the door with no success and trying to explain it away.

"Trying to impress me?" Raising an eyebrow, she sways a little in the hallway, her body canting towards him entirely without permission.

"Is it working?" She clicks her tongue at him, neither a yes or a no and leans forward to sneak a peek at what's in the mysterious room. It's dark and the crack is small but she manages to catch a whiff of an all too familiar scent. He pulls her back from the doorway, studies her, and deflates a little when he realizes she knows.

"Show me what you dragged me down here for, Rick." She presses her lips to his for an ephemeral moment, a small burst of a kiss before she crowds him and pushes him toward the door.

"Jeez, woman, patience." She feels the rumble of his excitement as it spreads through his body, his gratitude at how she shares in it. Pressed against his back like this, she can feel the tight sinew of his body caught with a boyish enthusiasm she finds much too attractive. When they pass through the door, the smell of chlorine hits her, much stronger than it was in the hallway.

Though the hurricane storms outside, select rays of moonlight scatter across the room, making the pool shimmer and shine, the light catching even the slightest movement of water. The lantern's glow mixes with the natural light, cascading over the room in a way that's much too enchanting to be reality. She looks over at Castle, his face ethereal as shadows soften the hard line of his nose and the light of the moon brightens his eyes until they gleam at her.

"Castle," he takes a step toward her, a question on his tongue and a need in his eyes, "it's beautiful."

Before she can reach out to pull him into her, she's against his chest and his mouth is working hers. Her arms wind around his neck, lips warm against hers as rain pelts the windows, and she knows it's a forever thing she's caught here. When she pulls away, the heat of his hands permeating her skin even through her sweater, his eyes stay closed. She leans back in, keeps her lips carefully away from his content smile, and touches the tip of her nose to his.

His eyelashes flutter, dark stripes against glowing skin, and his eyes open for her. The blue is darker here, almost midnight in the quiet chaos of the hurricane. He looks at her, soft and so very relieved, before hiding in the crook of her neck, fitting there like a puzzle piece. She curls her palm around the back of his head, so big compared to her hand, and pulls him back to look at her.

"So beautiful." The corners of his lips lift slightly, his eyes filled with a new light that she adores simply because she put it there. She leaves him then, slipping out of his grasp and into the dark. Reaching down, she pulls her shirt over her head and lets it drop haphazardly on the tile floor.

She looks up to see Castle's eyes wide, mouth hanging completely agape. Holding his gaze, she reaches back, unclasps her bra, and slowly drags the straps down her shoulders. His eyes darken, reaching a sparking sort of black when her bra finally falls to the ground. When she shimmies out of her sweatpants, she hears his quick gasp as he remembers she isn't wearing any underwear. But she doesn't look at him, doesn't even turn her head, only throws her pants behind her and dives into the pool.

She feels bumps erupt on her skin when she hits the water, but as she starts to move her limbs, propel herself, warmth rushes back under her skin. There's a deep whoosh behind her and when she turns her head, she sees Castle sinking to the bottom of the pool. His skin is a clear contrast to the water, bubbles floating around him from the jump. She stays there, weightless for a moment as she watches his muscles contract and his powerful legs kick. But then her lungs need oxygen and her legs are propelling her up, the air a welcome change as she breaks the surface of the glimmering water.

She shakes her head after she takes a breath, something she's done since she was a child, droplets of water flying in every direction as she wipes the chlorine from her eyes so she can see without the sting. He's swimming toward her when she opens her eyes again, the strong, careful strokes of someone who knows what they're doing that she admittedly didn't know he was capable of.

When he gets to her, both of them treading water in the middle of the pool as the moon casts its light over their lone forms, he beams at her in a way that makes his eyes crinkle and her heart stutter. His gaze dips beneath the water to her distorted body, skin seemingly moving with the water and legs too short. She narrows her eyes at him because it's what she has to do, part of the game they play, but he just continues to grin.

"Skinny dipping?" She raises an eyebrow at him, challenge and question in one as he voices his own.

"Like this wasn't your plan all along." He licks a droplet of water from his lower lip, tongue darting out to catch it before it falls where he can't reach. She feels herself floating toward him, her body canting toward him even when she's weightless.

"I had envisioned it with underwear, actually." She feels herself bump against his chest, one hand coming up to connect each of the freckles dotting his shoulder. Moving her finger across the spots, she makes a star, then turns each brown dot into one, tracing them into the big dipper.

"Mmm?" His skin is soft here with endless possibilities, a tree and a woman's profile and a house carved into his skin by the sun. She hears him chuckle deep in his throat, the sound rumbling through her skin and settling in her marrow. It'll be safe there, safe until she can give this joy back to him, whisper it into his pores and let it seep into his blood until it flows through him. And when his skin tears, joy and laughter and light will leak out.

"I like this better though." He nuzzles into her hair, places a soft kiss to the shell of her ear before speaking again. "I always like things better when they involve you and no clothing." His mouth lands just where her hair ends, tickling her scalp with warm breaths and the little hairs that run across her hairline, not fully grown and never hoping to be.

His mouth sluggishly makes its way down, stops at her cheekbone to worship the sharp edge before moving agonizingly slowly to her jaw. She tips her head back, feels drops of water racing down her neck. He licks them up, tongue shooting out to drink up the mixture of water and her. Her other hand comes to his shoulder, the freckles scattered across the expanse of skin long forgotten, grasping for purchase as she inhales sharply. She closes her eyes against it, the rain and the wind and the worries. His open mouth is on the corner of her lips, completely still and waiting.

She inhales, feels his skin warm and slick against her own, slants her impatient mouth over his too patient one and it's forever.

* * *

_So I know you can see the cover art in that teeeeeeeny little box up there, but it's awesome and PauliPorcupine made it so you should really check it out on my tumblr (allusiontoanillusion) because this is Pau's birthday fic and she deserves people fawning over her greatness. _


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